With just three days until the election, Sestak told CNN on Sunday, "Never do something that's not going to happen."

Sestak is challenging five-term Sen. Arlen Specter, who switched parties last year after 28 years as a GOP senator. The moderate Specter has been endorsed by President Barack Obama and the Democratic Party.

U.S. Rep Joe Sestak predicts he'll win Pennsylvania's hotly contested Democratic primary for U.S. Senate.With just three days until the election, Sestak told CNN on Sunday, "Never do something that's not going to happen."Sestak is challenging five-term Sen. Arlen Specter,...